This invention relates to coke ovens and, more particularly, to apparatus for cleaning the ascension pipes and the ascension pipe elbows employed on such ovens.
Coke ovens are generally equipped with one or two offtakes to carry off the volatile products liberated in the coking process. These gases pass through a duct in the oven's top and enter a vertically extending, refractory lined ascension pipe. These ascension pipes, which are also commonly referred to as standpipes, are connected at their upper ends to structures known as ascension pipe elbows. The ascension pipe elbows extend vertically from the upper end of the ascension pipe in a vertical leg and then curve outwardly and downwardly in a lateral leg to where they connect with a gas collecting main. Because the gases which are conducted in these pipes have entrained with them large amounts of carbonaceous solid material which tends to adhere to the inner surfaces of these pipes, the gas passages through the ascension pipes and the ascension pipe elbows will quickly become seriously restricted if these deposits are not regularly removed. To facilitate such removal, ascension pipe elbows are customarily designed with an access opening equipped with a cap valve known as an elbow cover. When this elbow cover is open, it vents the coke oven to the atmosphere and allows a cleaning instrument to be inserted through the access opening and into the interior of the ascension pipe and elbow. While this task may be performed manually, such manual cleaning is not a preferred method because it is time consuming and arduous. Further, because of the high temperature of the pipes and the elevated position of the work area, this procedure is also hazardous to the workmen carrying it out. This procedure may also present other dangers to these workmen since gases present in this work area have been alleged to be carcigenous. Consequently, a number of devices have been developed which allow for the mechanized cleaning of ascension pipes and ascension pipe elbows. A common characteristic of many of these devices is that they are mounted on a coke oven larry car which moves on tracks laid on the top of the oven and adjacent the ascension pipes. Many of these devices are equipped with a cleaning element which includes an extendable arm with a terminal cleaning head mounted thereon. The devices are positioned for use by moving the larry car until the cleaning element is adjacent to the ascension pipe. Thereafter, when the arm is extended the cleaning head is projected through the access opening and into the lateral leg. In certain designs, the device is capable, after the extendable arm has been withdrawn from the lateral leg, of being adjusted in position so that the cleaning element is disposed in a vertical position and aligned so that the arm may be moved and the cleaning head projected through the access opening and into the vertical leg of the elbow and into the ascension pipe. The aforementioned features are, for example, incorporated into the apparatus disclosed in U.S. Pat. No. 3,400,052.
A problem, however, may be encountered in the employment of such apparatus. Because the elbows may reach temperatures in the range of 1000.degree.-1500.degree. F. and because they are exposed to continually changing ambient conditions, it is found that they undergo thermal expansion or contraction such that they may be observed to bend or lean. Accordingly, it is also found that where the elbow access opening and the elbow itself may share a common vertical center line at one temperature, such a condition may not exist at an elevated temperature. Under conditions where elbows lean in this manner, the cleaning devices described above may be inefficient, for while they may be adjusted so as to initially align their cleaning elements with the access opening, they lack the capacity to compensate for thermally caused misalignments between the access opening and the legs of the elbow itself. It is, therefore, the object of the present invention to provide a cleaning apparatus which, after it is initially aligned with the elbow opening, may thereafter be further aligned to compensate for thermal misalignment in the elbows.